and before the normal License panel. It appears there is something being

tested before that Nsi section that is failing.

Yes, the installer reads the the uninstall information from the registry key. If it exists, it assumes ooSQLite is installed. Then, if ooSQLite is installed, it tries to test that there is no ooSQLite program running and that the PDF doc is not open. It does that by copying the two files and then trying to delete the originals. If the files do not exist this fails

So, when you uninstall ooRexx by deleting the whole tree, the registry key is not removed. The files are deleted and when you go to install ooSQLite it fails as described above.